A well sharpened skate blade must be uniformly ground along its entire sharpened length. This is conventionally achieved by moving the skate along a grinding wheel and depending on a skilled operator to uniformly apply grinding pressure while maintaining a steady relative speed between the grinding wheel and blade. Uniformity in both pressure and speed is necessary to avoid excess grinding at points along the blade.
Two types of sharpeners are predominant in the field. Most popular is the table-top machine in which a horizontally-clamped skate, floated on arms or slid across the table in a fixture, is manually pushed back and forth against a stationary, horizontal grinding wheel. Grinding pressure is entirely a function of operator-applied forces. Less familiar is the vertical-clamp sharpener in which a vertical grinding wheel, supported by a linkage and spring, is manually drawn over an inverted, vertically-clamped skate. Grinding pressure depends on the fraction of the grinding wheel weight not supported by the linkage and spring. But (absent operator correction) conventional vertical-clamp sharpeners produce substantial variations in grinding pressure at the blade extremities, and some (particularly those with overhead springs as support for the grinding wheel) vary sharpening speed at the blade extremities due to horizontal forces imparted by the spring. Further, neither the table-top nor the vertical-clamp sharpener presently employ any means to assist the operator in achieving uniformity in sharpening speed. All of which leads, without the careful attention of a skilled operator, to poor sharpening quality.